Signaling gateways are network components operable to translate signaling messages between different network types. For example, a signaling gateway may be used to translate portions of signaling messages transmitted between an Internet protocol (IP) network domain and the public switched telephone network (PSTN) domain. In one example, an SS7/session initiation protocol (SIP) gateway (SSG) may translate between SS7 transaction capabilities application part (TCAP) messages and SIP messages.
SIP provides a signaling and call setup protocol for IP-based communications, such as communications in an IP multimedia subsystem (IMS) network environment, that can support call processing functions and features present in PSTN. There is a desire in the telecommunications market to extend the services provided by SIP to the PSTN domain. This involves providing SSGs for enabling SIP nodes in the IP domain to communicate with network elements in the SS7 domain. An SSG enables the transfer of AIN-based service messages to SIP nodes for invoking SIP-based services.
One difficulty with using SSGs for communicating messages from the SS7 domain to SIP nodes in the IP domain is the identification of SIP nodes. In one technique for identifying SIP nodes, the SSG has a one-to-one mapping with a SIP node. For example, when an AIN/IN trigger is detected at a service switching point (SSP), the SSP communicates an SS7 query message to an SSG, which generates a SIP query message corresponding to the SS7 query message and communicates the SIP query message to a mapped SIP node. This technique ties a SIP element to a particular SSG and results in low flexibility and scalability.
In another technique for identifying SIP nodes, an SSG may have provisioned directory number ranges supported by each SIP node. For example, first and second SIP nodes may support directory numbers 212-213-0000 to 212-213-5555 and 212-213-5556 to 212-213-9999, respectively. An SSG may include a database of the directory numbers and corresponding SIP nodes for determining an appropriate SIP node to communicate received SS7 messages. This technique may be disadvantageous because it requires that the SSG maintain a database for the directory numbers. For example, any time directory number provisioning changes occur in either the SS7 domain or the IP domain, changes may be required at the SSG. If a SIP node supports directory number 212-213-0000, and the number is moved to another SIP node, the change must be propagated to the SSG maintaining the directory number.
Accordingly, in light of these difficulties described above, there exists a need for improved methods, systems, and computer program products for routing messages to SIP nodes.